Stabilizing dyed hydrocarbon liquids



Patented Aug. 25, 1936 UNITED STATES PATENT OFFICE Nathaniel n. Rickles, Roselle, N. 1., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 30, 1933, Serial No. 704,794

6 Claims. (01. is-9) The present invention relates to novel methods of stabilizing dyed light hydrocarbon liquids and to the products obtained thereby.

As is well known in the art, solutions of oilsoluble dyes dissolved in light hydrocarbbn liquids, such as are used as motor fuel, tend to fade when exposed to sunlight. Various attempts have been made in the past to overcome this objection by adding oxidation inhibitors to the solution, but the present invention accomplishes the desired result of preventing fading of dye in the solution by the addition of a type of material entirely different from the addition agents used heretofore.

Broadly, the invention comprises the addition of organic soaps to stabilize the dye in a light hydrocarbon liquid. The invention is typified by the addition of cobalt naphthenate to a gasoline containing a red dye such as that known commercially as G. R. 0. Red. This dye is a couple diazotized xylidine with beta naphthol, Schulte No. 75, CiaHisNzO, having the following graphic formula:

OH; HO

By "naphthenate is meant the soap of naphtheni'c acids such as are recovered from cracked petroleum dlstillates.

Broadly, the soaps to be used include heavy metal soaps such as cobalt or manganese soaps of olelc or linoleic acids, naphthenic acids, recovered from cracked petroleum distillates and synthetic acids prepared by the oxidation of petroleum oils and waxes. It has been found that these soaps will stabilize and prevent fading of a dye added to light hydrocarbon liquids such as a gasoline motor fuel when exposed to sunlight. The amount of the soap to be used depends upon a number of factors, such as the type of gasoline or other liquid being used, as well as the type of dye and the length of time for which it is intended to protect the dye against fading. Generally, however, from .005 to 1% will serve as suitable limits in the concentration of the soap and it has been found preferable to use between .01 and .1%.

The light hydrocarbon liquid may be, for example, a petroleum or coal tar naphtha, a hydrogenated naphtha, a cracked naphtha, or the particular cuts of naphtha or gasoline such as are commonly used as motor fuels, or it may consist of blends of any such light petroleum hydrocarbons with liquids such as benzol, alcohols, and the like. It may also consist of light polymers produced by polymerization of unsaturates or fractions of dry distillation or carbonization products of lignite, coal, peat, shale, and the like. When such liquids or blends are used as fuel for internal combustion engines, it is often desirable to add other ingredients such as anti-knock agents (in-- 'cluding lead tetraethyl, tin tetramethyl, iron carbonyl, etc.) or upper cylinder lubricants, carbonpreventing compounds, etc. Although the present invention relies upon the addition of soaps of the types referred to in order to prevent fading of any dye added to the light hydrocarbon liquid, still it may be desirable and is included within the invention to use a small amount of a gum or oxidation inhibitor in conjunction with the dyestabilizing soap. Suitable inhibitors may be any of the well known types such as alpha-naphthol and various other hydroxy or amino compounds.

The dyes to be used in solution in the light hydrocarbon liquid may be any of the oil-soluble types, especially those of the so-called Soudan type, although other types such as the alizarin or anthraquinone types may also be used. Various colors may be used such as red, blue, orange, green, etc. as they appear on the market in the form of dyed gasoline for use as motor fuel, or in the form of any other light hydrocarbon liquid products. Although the exact mechanism of the stabilizing action of applicants soap on the dye in solution in the light hydrocarbon liquid is not well understood, yet it is believed not to depend upon the specific structure of the particular dye and therefore is believed to apply to any of the oil-soluble dyes or at least to any dye subject to fading when a solution thereof in a light hydrocarbon liquid is exposed to sunlight. The amount of the dye to be msed may vary overa fairly wide range according to the intensity of the color desired in the finished solution. Generally, from .001% to .1% dye will be sufficient.

In carrying out the invention it has been found desirable to add the soap to the gasoline or other light hydrocarbon liquid after the dye and any other ingredients or addition agents have been incorporated with the gasoline. When the soap is added it should be permitted to dissolve or swell for a sufficient lengthof time to permit practically maximum increase in viscosity for the amount of soap being used. This may require from several hours up to 24 hours or more, depending upon the soap used. Heat and agitation may be employed to accelerate the dissolving or swelling of the soap in the light hydrocarbon liquid.

The following examples are given as illustrative of the invention:

Example 1 An orange dyed commercial gasoline ordinarily used as motor fuel was exposed to the sunlight. In four days the color changed to water white. A similar sample of motor fuel to which had been added .01% of cobalt naphthenate did not fade in color during the same. exposure to sunlight.

Example 2 The use of .01%of cobalt naphthenate stabilized the red dye in a gasoline motor fuel containing a small amount of lead tetraethyl as anti-knock agent.

An oxidation breakdown test on a. sample of gasoline with and without .01% of cobalt naphthenate but without any dye, indicated that the metal soap did not act as an oxidation inhibitor.

Although the invention has been described as particularly applicable for the stabilization of dyes in gasoline motor fuels, it is not limited to that particular use but it can also be applied to the stabilizing of dyes in solidified fuels, solvent naphthas, and in light hydrocarbon liquids such as are used in paints and varnishes, etc.

The foregoing description is merely illustrative and various changes and alternative arrangements may be made within the broader scope of the invention and in the appended claims it is intended to claim all novelty inherent in the invention as broadly as the prior art permits.

I claim:

1. The method of stabilizing dyes normally subject to fading in sunlight in solution in a light hydrocarbon liquid having a boiling range corresponding approximately to that of motor gasolines, solvent naphtha and benzol, which comprises adding to said solution about .005 to 0.1% of a soap of the group consisting of reaction products of cobalt and manganese with acids selected from the group consisting of oleic acid, linoleic acid and naphthenic acids recovered from cracked naphthas.

2. A composition comprising a major propor tion of a light hydrocarbon liquid having a boiling range corresponding approximately to that of motor gasoline, solvent naphtha and benzol, together with a small amount of dye soluble therein and normally susceptible to fading in sunlight in solution in said hydrocarbon liquid, and .005 to 0.1% of a soap of the group consisting of reaction products of cobalt and manganese with acids selected from the group consisting of oleic acid, linoleic acid and naphthenic acids recovered from cracked naphthas.

3. Product according to claim 2 containing an oil-soluble dve selected from the group consisting of Soudan, alizarin and anthraquinone type dyes.

4. Product according to claim 2 containing a small amount of lead tetraethyl.

5. A motor fuel comprising a major proportion of gasoline, from. 0.001 to 0.1% of an oilsoiuble red dye of the Soudan type and from 0.005 to 0.1% of a cobalt soap of naphthenic acids recovered from cracked naphtha.

6. Product according to claim 5 in which the dye is a couple diazotized xylidine with beta naphthol, Schulte No. 75, C18H18N20, having the formula (CH5) 2CeH3NZNC1oI-IeOH.

I NATHANIEL H. RICKLES. 

